Transcript Android Boot Camp for Developers Using Java, Comprehensive

Android Boot Camp for Developers Using Java,
Comprehensive: A Guide to Creating Your First
Android Apps
Chapter 9: Customize! Navigating with a Master/Detail Flow
Activity on a Tablet
Android Boot Camp for Developers Using Java, 2nd Ed.
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Objectives
In this chapter, you learn to:
• Understand responsive design for Android apps
• Create an Android tablet project using an application
template
• Understand the Master/Detail Flow template
• Modify the Master/Detail Flow template
• Add a WebView widget
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Objectives
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(continued)
Display a Web browser within a tablet app
Add an Internet permission to the Android Manifest
Customize the content of the sample template file
Display a custom layout in the details pane
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Understanding Responsive Design
• Responsive design
– An approach to
designing apps
and Web sites that
provide an optimal
viewing experience
across as many
devices as possible
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Using Application Templates
• Application templates
– Used to create basic Android applications that can
immediately be run and test on an Android device
of any size
– Android templates are
available when you
create a new Android
project
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Using Application Templates
(Continued)
Understanding the Structure
of the Master/Detail Flow
Template
– Several Java and XML layout resource files have
been created automatically
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Using Application Templates
(Continued)
SRC Files
– ItemDetailActivity.java
• The purpose of this class is to display the activity_item_detail.xml
layout file if a smartphone is detected
– ItemDetailFragment.java
• The purpose of this class is to display the
fragment_item_detail.xml layout file
– ItemListActivity.java
• The purpose of this initial Activity is to display the master list in a
two-pane mode if a tablet device is detected or to launch a second
Activity to display the detailed items if a smaller device is detected
– ItemListFragment.java
• The purpose of this class is to display the activity_item_list.xml
layout file
– DummyContent.java
• The purpose of this Java file is to provide sample code you
customize to suit your specific app content.
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Using Application Templates
(Continued)
Layout Files
– activity_item_detail.xml
• When a smartphone is detected, the app uses this layout to
display the FrameLayout instance
– activity_item_list.xml
• When a smartphone is detected, the app uses this layout to
display the master list fragment
– activity_item_twopane.xml
• When a tablet is detected, the app is displayed in a twopane layout containing both the master item list fragment
and the item detail container
– fragment_item_detail.xml
• When a smartphone or a tablet is detected, this layout file
displays the detail pane using the onCreateView( ) method
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Using Application Templates
(Continued)
• Adding Images to the Drawable
Folder
– If necessary, expand the src and
layout folders in the Package
Explorer
– Drag the image files to the
drawable-hdpi folder until a plus
sign pointer appears
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Designing an XML TableLayout
• The Strings table is responsible for the text
displayed in the app
– The first string is displayed in the title bar of the
tablet, and the second string is displayed in the title
bar of a smaller device such as a smartphone
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Designing an XML TableLayout
Android Boot Camp for Developers Using Java, 2nd Ed.
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Designing an XML TableLayout
Android Boot Camp for Developers Using Java, 2nd Ed.
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Designing an XML TableLayout
Android Boot Camp for Developers Using Java, 2nd Ed.
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Creating a TextView XML Layout for
the Second List Item
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Creating a WebView XML Layout for
the Third List Item
• Webview
– A View widget
object that
displays Web
pages
• Permission
– A restriction limiting access to a part of the code or
to data on the device
Code Syntax
android:permission="android.permission.INTERNET"
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Creating a WebView XML Layout for
the Third List Item
(continued)
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Creating a WebView XML Layout for
the Third List Item
(continued)
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Creating a WebView XML Layout for
the Third List Item
(continued)
• A fragment is a piece of an application’s user
interface or behavior that can be placed in an
Activity
– Fragments are essentially a sub-Activity hosted inside
another Activity
• To determine if two String objects match exactly:
– Use the .equals method, and not the == operator
– The == operator compares if two objects are exactly the
same object.
– Two strings may be different objects, but have the same
exact characters
– The .equals() method is used to compare strings for
equality
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Creating a WebView XML Layout for
the Third List Item
(continued)
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Creating a WebView XML Layout for
the Third List Item
(continued)
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Running and Testing the Application
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Tap or click Run on the menu bar
Select Android Application from the dialog box
Save all the files when prompted
Unlock the emulator (if necessary)
Test each tab to ensure it works as intended
– You must have Internet connectivity to open the Web
page and enough memory available to handle the
app connection to the Web
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Summary
• Responsive design is an approach to designing apps and
Web sites that provide an optimal viewing experience across
as many devices as possible
• Android templates are available when you create a new
Android project and are used to create basic Android
applications that you can run and test on an Android device
of any size
• A tablet app created with the Master/Detail Flow template
displays a Master list of items in a narrow vertical pane along
the left edge of the screen
• To display the detail content for the first list item in the Bike
and Barge app, you provide images and text descriptions in
an XML TableLayout. Each row in the TableLayout displays
an ImageView and TextView control
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Summary
(continued)
• To display the detail content for the second list
item, you code two TextView controls in a Linear
layout that include the tour details
• To display the detail content for the third list item,
you customize the default fragment_item_detail.xml
layout to use a WebView object instead of a
TextView object
• After including a WebView object in the XML layout
of an app, you must add the INTERNET
permissions to the Android Manifest file so the app
can access the Internet and load Web pages
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Summary
(continued)
• To associate the content displayed in the detail
pane with each list item in the left pane, you
customize the DummyContent.java class file by
adding code to the addItem statement so it
references three String objects: the id, the item list
string, and the Web site URL
• To handle the responses to user selections, you
add conditional statements to the
ItemDetailFragment.java file
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